BOSTON (AP) — A European security official with knowledge of the investigation into twin bombings at the finish line of the Boston Marathon says initial evidence indicates they were not detonated by suicide bombers.

The official spoke from the United States on condition of anonymity because he was not authorized to speak about the U.S. investigation. He says, "investigators believe it was not the work of suicide bombers" but it's still too early to know for sure.

The bombs blew up seconds apart Monday at the finish line of one of the world's most storied races, killing at least three people, including an 8-year-old boy, and wounding more than 140 more.